Technical Field
The present disclosure relates to the handling of drilling rods or pipes and additional devices for earth drilling; in particular, to the making and unmaking of a sequence of drilling rods in a drilling machine.
Background
Various drill rod carousel or magazine devices are in general use today with a drilling rig for handling and storing sections of drill rod. (The terms “drill rod” and “drill pipe” are considered interchangeable.) Drilling rigs of this type typically have an upright mast with a drill table or floor at the lower end thereof and a rotary drive mechanism (also called a “rotary head” or “top drive”) mounted on the mast for linear movement along the mast as the drill string is drilled into the earth in a generally vertical direction. In conventional blast-hole drillings, the drilling angle may not be vertical, and often only shallow holes are necessary; therefore, one thirty to fifty-foot section of drill rod remains attached to the rotary head with a drill bit attached to the lower end thereof. As the drill rod is rotated, a downward force is controlled by the rotary head, causing the drill bit to drill the hole in the earth. When the drill bit has reached the required depth, it is retracted up into the mast, and the portable drilling rig is relocated to the next location where a blast hole is to be drilled.
When it becomes necessary, however, to drill holes deeper than the single pass capability of the drill, (i.e., the length of a single drill rod section, which may be shortened), a plurality of drill rod sections are attached end to end, forming a drill string for boring this deeper hole. In this case, the initial drilling section must be released from the rotary head and the following drill rod sections connected between the drill string and the rotary head. Conventionally, these following drill rod sections are carried by a drill rod carousel or magazine which is housed on or within the mast. The carousel rotates about an axis parallel to that of the drill hole in the earth and positions these drill rod sections in line with center line of the drill hole.
A typical drill rod carousel has a plurality of cups or sockets at the lower end thereof, each for retaining the lower end of a drill rod section. The end of the drill rod typically has flat surfaces for engaging corresponding flat surfaces in the cup. At the point the rod is put into the carousel, the joint between the drill rod and the rotary head is still at a relatively high torque from drilling. The rod is thus required to lock into the carousel cup so that the top drive can be unthreaded from the drill rod.
The drill rod carousel is pivotally connected to the mast so that it, as a unit, may pivot in or out from a stored position to an operating position where one of the drill rod sections is in line with the rotary head and drill hole. In this operating position, the rotary head is lowered to attach the rotary driving spindle to the male threads at the top of the drill rod. With this connection made, the rotary head is raised, removing the lower section of the drill rod from its carousel cup. Next, the carousel is pivoted back to the stored position, out of the way, so that the rotary head may be lowered and the lower end of the drill rod section connected to the upper end of the drill rod section already in the hole. In some drilling machines, the carousel is pivoted out of the way in front of the tower structure, but this has no effect on carousel operation.
After drilling a depth equal to the length of the drill rod section, the top of the section of drill rod remaining in the hole is secured to prevent it from rotating, the rotary head spindle is unscrewed from the drill string and the rotary head raised to the top of the mast so that the carousel may again be pivoted into place, aligning a following section of drill rod with the rotary head and drill hole, after which the process repeats itself as described.
Existing designs for drill rod cups in the carousel require the flats of the drill rod to be aligned with the flats of the cup; thus the rotation of the rod must be stopped before it enters the cup. Conventionally, a lead-in chamfer in the rod cup was provided to prevent jamming of the rod in the top of the cup, making it easier to get the drill rod to enter the cup. Entry of the rod into the cup to engage the flats is still difficult to achieve in the conventional design, as not all cups have an indication of where the flats are in the cup. Even with an indication of the location of the flats in the cup, if the angular alignment of the respective flats on the rod and in the rod cup is off by even a small angle, this may still prevent smooth entry of the rod into the cup. What is needed is a rod cup that allows the drill rod to drop down into the cup while rotating and engage the cup flats without further manual alignment by an operator.
The reader should note that this disclosure is not limited to the handling of drill rods for blast-hole drilling, but is applicable to other types of drilling, such as for water wells or petroleum-producing wells, or the handling of connected tubular parts generally.